Unfortunately, the poem in Jonah 2 is v. tough (my first-year students
fought their way through it this week; when we got to the end, one
exclaimed, "Narrative! What a relief!"), and Ruth has a number of anomalous
forms and constructions.
I recommend reading either "Abraham" (Gn 11.27-25.11) or "Joseph" (Gn 37-50;
ch. 49 is challenging).
You will also find much of the narrative books (Joshua, Judges, Samuel,
Kings) straightforward, watching out for poems; Ezra has Aramaic sections;
Esther does not "feel" quite like the Hebrew of most grammars; Chronicles is
quite readable, especially once past the opening genealogies (they are easy
to read, but ... they are genealogies).